The present invention relates generally to the field of augmented reality displays, and more particularly to both: (i) direct augmented reality displays where some of what a user's eye sees is light received directly from a target object (for example, an augmented reality windshield of a motor vehicle), and (ii) indirect augmented reality displays where the entire display is based on video signals, rather than direct viewing (for example, an augmented reality view based largely on a feed from a remote security camera).
Personal Heads Up Display (HUD) devices are augmented reality display devices made for vehicles. The augmentation of the view through the vehicle windows means that the driver can keep her head up more (for example, not look down at the dashboard, thereby taking her eyes off the road, to check the fuel gauge). Currently, most HUD systems are designed to augment the information available to the user. HUDs and/or helmet mounted displays have been used in military aviation to augment the perception of a user. One goal here is to allow critical information to be displayed to a user while they are focusing on in the far-field, as opposed to at the screen itself. This is typically achieved by using a projector combined with a reflective prism or glass surface allowing the projected image to be combined with the incoming light from the far field. This approach typically does not significantly compromise the native vision of the user.
Another known technology for altering the visual appearance of the far-field is to use active and passive polarizing materials such as LCD (liquid crystal display) lenses. LCD lenses are used in active 3D projection or other technologies such as welding helmets. In both of these cases, the technology regulates the light transmitted to each of the eyes, where the smallest regulating unit is one lens (that is, substantially the entire light arriving at the eye).
One additional piece of augmented reality display terminology will now be introduced. As used herein, a “base image” is a real, or virtual view that corresponds to what a viewer would see if an augmented reality display were not augmented. In a “real” base image, this view consists primarily of objects (for example, a horizon, a tree) that actually exist in the real world. In a “virtual” base image, the view would consist primarily of objects that are made to look (at least to some degree) like they exist in the real world. This “base image” is distinguished from the “augmentation portion” of the augmented reality display, which augmented portion changes what is shown in the base image to convert the base image into an augmented reality image. Both direct augmented reality images and indirect augmented reality images will generally include both a base image and augmentation portion.